Reference may be made to my prior U.S. Pat. Nos: 5,344,072; 4,967,955; 4,821,957; and to my prior U.S. patents cited as references in the aforementioned patents.
Adjustable rail anchorages are subject to very large lateral loads applied to the rails, particularly in crane rails by cranes as they travel along the rails, being cranes used for material handling in industrial facilities. Such cranes travel along rails which are supported generally on steel structures, the rails being maintained in the required position by rail anchorages that have to ensure that the rails remain located when very substantial lateral loads are generated, for example, when the crane is in motion. It is therefore important that the rails properly guide the cranes by being correctly aligned. Poorly aligned rails result in crane wheel wear and wear to the sides of the rail head and cause the crane to skew and bind against the rail. As a consequence even larger lateral forces can be generated on to the rail as the crane skews and binds. By providing an anchorage that is laterally adjustable the lateral alignment of the rail can be more easily established and maintained. However, when the rail anchorages offer adjustability other problems can occur. They can slip due to contamination by oil and grease which can drip from the crane axle and bearings as the crane travels along the rail. The oil and grease can lubricate the sliding surfaces of the adjustable anchorage. Also, adjustable rail anchorages are generally installed by a threaded bolt or threaded stud which requires careful attention that adequate torque is applied to the bolt or nut in order to prevent slipping of the anchorage.
Cam devices have been used in rail anchorage devices as a means of adjustment. Attempts have been made to prevent untoward cam rotation by use of incremental locking positions, which have the result that only incremental adjustments are possible. The bolt or other fastening device provided has been placed centrally within a hole in the cam. In the prior art the application of the lateral load from the rail to the clip does not increase the frictional resistance of the cam against rotation within the rail clip.
In existing adjustable rail clips that are adjusted with a cam, the cam is a relatively bulky element. Consequently, the secondary element into which the cam is installed is also relatively large. This secondary element usually contacts the rail and is called a clip body. By reducing the size of these elements, but maintaining the strength, the rail clip can be installed in situations previously impossible to install an adjustable rail clip, or the same sized rail clip can be installed but having more lateral adjustment.
FIGS. 1 & 2 represent a cam in the prior art. FIG. 1 is a side view and FIG. 2 is a plan view. The upper and lower parts of the cam are 1U and 1L respectively. The lower part of the cam 1L is a circular boss. There is an opening 1p in the upper and lower parts of the cam which is continuous. If a bolt is assembled inside this opening in the cam, the bolt is totally enclosed, in the plane perpendicular to the length of the bolt, by the opening in both the lower and upper parts of the cam. The walls of the opening encompass the bolt including at positions 1a and 2a, which is the narrowest part of the circular boss 1a.
It is desired to provide a smaller, more efficient, adjustable rail clip in plan view or bird's eye view, yet still have the same strength to resist lateral forces applied by the rail to the rail clip.